>>You will drive up the price, but not too much. You are tweaking the wrong side of economics. Make carrying such a gun or keeping it on premise a crime. Make any crime using a military grade weapon a higher risk by driving up sentences via mandatory addition.In case self defense was done with a military weapon and the weapon cannot be explained legally, make a case. Do searches for the weapons ONLY, not trying to make a case if anything else was found - searches without a warrant might cause less problems then.
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>All good ideas but what is wrong with prohibiting their manufacture?

Just note what you said:

>>>>>>>>>>>There is absolutely no justification for manfacturing this kind of weapon for other than military or police use.

I don't see how does a production line know where the product will end. The mere existence is enough. If it exists, it will most surely be used for purposes not intended. It may be salvaged from a crashed police car, it may be stolen in many ways, it may be smuggled back from any of those military bases abroad, it may vanish from the lists in so many ways and magically reappear anywhere, a cop in wrong part of town may be overconfident when carrying such a weapon and may fall into a trap where he can't use it but can lose it etc etc.

It's osmosis. If it exists on one side of a membrane, it will seep to the other.